LOL!
Seriously, I looked for some for songwriters to keep organized - gave up on it - too limited or too expensive or both.
I bought MasterWriter several years ago and tried to use it but finally just stopped. Not nearly useful enough to justify the hassle and expense. I still load it from time to time for rhyming ideas. I bought Rhyme Genie for rhyming and use it occasionally. It has a quirky interface I do not care for. Nowadays for rhymes I go to
http://www.rhymezone.com/ or
http://www.wordhippo.com/For writing I find nothing beats Notepad or Wordpad or similar on my phone. I just need a way to capture and store the lyrics. I will resort to pencil and paper if my phone is dead but greatly prefer something more permanent and easy to store and access.
And for recording ideas I also use my phone. Got a melody or riff idea? Ya better record that immediately or lose it 5 minutes from now. So the phone works for both lyrics and melody. One device to rule them all!